Preliminary Information
MT9076
Frame # Ft
Fs Notes Frame # Ft
Fs Notes Frame # Ft
Fs
Notes
1
2
1
0
1
0
1
0
1
0
1
0
1
0
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
1
0
1
0
1
0
1
0
1
0
1
0
C
o
n
c
e
n
t
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
1
0
1
0
1
0
1
0
1
0
1
0
0
0
0
1
1
1
0
0
0
1
1
1
R
e
s
y
n
c
h
r
X
X
X
X
X
X
X
X
X
X
X
S
S
S
C
C
C
A
A
L
S = Spoiler Bits
3
4
5
6
C = Maintenance Field Bits
7
8
r
9
a
t
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
o
n
i
o
r
A = Alarm Field Bits
z
a
t
F
i
i
e
l
L = Line Switch Field Bits
o
n
d
L
d
a
t
B
i
L
t
L
a
s
S
S = Spoiler Bits
Table 9 - SLC-96 Framing Structure(T1)
3.3
E1 Digital Interface
PCM 30 (E1) basic frames are 256 bits long and are transmitted at a frame repetition rate of 8000 Hz, which
results in an aggregate bit rate of 256 bits x 8000/sec = 2.048 Mbits/sec. The actual bit rate is 2.048 Mbits/sec
+/-50 ppm encoded in HDB3 format. The HDB3 control bit (page 01H, address 15H, bit 5) selects either HDB3
encoding or alternate mark inversion (AMI) encoding. Basic frames are divided into 32 time slots numbered 0
to 31, see Figure 31. Each time slot is 8 bits in length and is transmitted most significant bit first (numbered bit
1). This results in a single time slot data rate of 8 bits x 8000/sec. = 64 kbits/sec.
It should be noted that the Mitel ST-BUS also has 32 channels numbered 0 to 31, but the most significant bit of
an eight bit channel is numbered bit 7 (see Mitel Application Note MSAN-126). Therefore, ST-BUS bit 7 is
synonymous with PCM 30 bit 1; bit 6 with bit 2: and so on (Figure 31).
PCM 30 time slot 0 is reserved for basic frame alignment, CRC-4 multiframe alignment
and
the
communication of maintenance information. In most configurations time slot 16 is reserved for either Channel
Associated signaling (CAS or ABCD bit signaling) or Common Channel signaling (CCS). The remaining 30
time slots are called channels and carry either PCM encoded voice signals or digital data. Channel alignment
and bit numbering is consistent with time slot alignment and bit numbering. However, channels are numbered 1
to 30 and relate to time slots as per Table 10.
PCM 30 Timeslots
0
0
1,2,3...15
1,2,3...15
16 17,18,19,... 31
16 17,18,19,... 31
Voice/Data Channels
(DSTi/o and CSTi/o)
Table 10 - ST-BUS vs. PCM-30 to Channel Relationship(E1)
27
MITEL [ MITEL NETWORKS CORPORATION ]
